content: /*
   * Copyright 2016-present David Karnok
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *     http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package hu.akarnokd.rxjava3.async;
  
  import org.reactivestreams.Subscriber;
  
  import io.reactivex.rxjava3.core.Flowable;
  import io.reactivex.rxjava3.exceptions.Exceptions;
  import io.reactivex.rxjava3.functions.Supplier;
  import io.reactivex.rxjava3.internal.subscriptions.DeferredScalarSubscription;
  
  /**
   * Runs a Supplier and treats a null result as completion.
   *
   * @param <T> the value type
   */
  final class FlowableFromSupplierNull<T> extends Flowable<T> implements Supplier<T> {
  
      final Supplier<? extends T> supplier;
  
      FlowableFromSupplierNull(Supplier<? extends T> supplier) {
          this.supplier = supplier;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super T> s) {
          CallableNullSubscription<T> deferred = new CallableNullSubscription<>(s);
          s.onSubscribe(deferred);
  
          if (!deferred.isCancelled()) {
  
              T v;
  
              try {
                  v = supplier.get();
              } catch (Throwable ex) {
                  Exceptions.throwIfFatal(ex);
                  if (!deferred.isCancelled()) {
                      s.onError(ex);
                  }
                  return;
              }
  
              if (!deferred.isCancelled()) {
                  if (v == null) {
                      s.onComplete();
                  } else {
                      deferred.complete(v);
                  }
              }
          }
      }
  
      @Override
      public T get() throws Throwable {
          return supplier.get();
      }
  
      static final class CallableNullSubscription<T> extends DeferredScalarSubscription<T> {
  
          private static final long serialVersionUID = -7088349936918117528L;
  
          CallableNullSubscription(Subscriber<? super T> downstream) {
              super(downstream);
          }
  
      }
  }
  